Scientists celebrated another success with the Japanese probe Hayabusa 2 on Wednesday night (US time), when the robot explorer made a second precise landing on the Ryugu asteroid, to collect a blank dust sample and rocks excavated by an explosive impactor. earlier this year.
Using rocket boosters to control its descent, and guided by a laser range finder, Hayabusa 2 approached chilly Ryugu on autopilot on Wednesday, slowing to a relative speed of about 10 centimeters per second in the final phase of the landing.
Hayabusa 2 maneuvered on a luminous navigation aid issued on the surface of the asteroid earlier this year to mark the landing site, and then started the last descent, the probe's sampling horn extending from the front of the spacecraft.
Telemetry data and images obtained from Hayabusa 2 show that the probe landed briefly on the asteroid at 21:06. He was starting to move away from Ryugu a few seconds later, emitting pulsations to counter the low gravity of the asteroid half a mile wide (900 meters wide).
About four hours later, at a press conference, officials described the brief landing as a success after the mission's first landing at Ryugu in February.
"Hayabusa 2 performed a second touchdown today and we were able to get information on the history of the solar system," said Yuichi Tsuda, project manager for Hayabusa 2 at the Japan Aerospace Exploration Agency.
Ground crews applauded as the flow of data from the probe, orbiting the sun, and Ryugu blocked more than 244 million kilometers from Earth, confirmed the hit.
Launched in December 2014, Hayabusa 2 is Japan's mission to visit an asteroid and collect samples for their return to Earth. Scientists are eager to analyze specimens of Ryugu, a dark asteroid rich in carbon, essential element of life.
Researchers will study the samples to find clues about the formation of the solar system 4.6 billion years ago and perhaps the origin of water and life on Earth .
Last month, mission officials decided to send Hayabusa 2 a second sampling of rock and dust from a second site at Ryugu, providing scientists with more varied documentation to consider when mission will return to Earth at the end of next year.
The Hayabusa 2 sampling mechanism is to send a metal bullet into the asteroid as soon as the probe's sampler horn comes into contact with the surface. The projectile is designed to force fragments of rock and dust through the sampler's horn into a collection chamber inside a spacecraft.
Takanao Saiki, Hayabusa 2 project engineer and JAXA flight director, told reporters at a press conference on Thursday that probe data showed that the temperature had increased in the projectile firing mechanism at the time. landing, suggesting that the system was working as intended.
Three images taken by an on-board camera aboard Hayabusa 2 showed the sampling horn in contact with the asteroid, then violently projecting debris from the surface. Countless small fragments of asteroids were visible around the probe in the final snapshot of the three-image sequence released by JAXA.
"The third photo is really amazing," said Makoto Yoshikawa, Hayabusa 2's Mission Manager. "It's really great, a lot of rock fragments are flying out."
"It's a wonderful picture, I think," Tsuda said. "Hayabusa 2 hit the surface of Ryugu, so it's a proof."
Another view of the landing site taken by the Hayabusa 2 navigation camera shows a cloud of debris left a few moments after the asteroid's spacecraft took off.
Once the second and final sample collection was complete, Hayabusa 2 began to recover to an initial position about 20 km from the asteroid. The spacecraft has closed the sampling device lid containing the asteroid, and the ground crews will then send commands to seal it inside the re-entry jar that will transport the material into the Earth's atmosphere. the end of the mission.
"There is nothing I can complain about, everything worked perfectly," Tsuda said through a translator. "It was a perfect operation, so … it's a score of 1,000 out of 100".
Samples collected Wednesday are not just from the first sampling of Ryugu, but scientists have explained that the newly captured materials came from the surface of the asteroid, where they could have escaped radiation and other effects of weathering. space for billions of years.
The primitive samples were exposed during a bold and unprecedented bombardment by the Hayabusa 2 probe in April. The probe deployed an explosive charge to fire at high speed on the asteroid, sculpting a new crater and projecting buried materials around the impact site, ready to be recovered by Hayabusa 2.
"We decided to get samples in this area so we could sample the subsurface materials … and since our operation was perfectly conducted, we can see that we have obtained subsurface samples," said Seiichiro Watanabe, Hayabusa 2 Project scientist from Nagoya University.
"Bringing the subsurface materials back to Earth will be something no other country can do in the next 20 years," Watanabe said.
The Hayabusa 2 sample rack has three chambers to separate collected materials from each landing. Officials decided to go ahead with the second sampling after evaluating the scientific benefits and technical risks of the maneuver, but with two samples aboard the spacecraft, the mission leaders do not anticipate to try a third sampling.
While Hayabusa 2 explores Ryugu, NASA's OSIRIS-REx mission examines the asteroid Bennu before collecting a sample at this location in 2020 to then return it to scientists on Earth in 2023.
OSIRIS-REx is designed to bring home at least 60 grams, or 2.1 ounces of Bennu samples, far more than Hayabusa 2. However, OSIRIS-REx only needs to collect one sample from Bennu's surface. .
NASA and JAXA agreed in 2014 to share their asteroid samples.
Named after the famous Japanese tale of a dragon palace, the Ryugu asteroid performs a sun tour every 1.3 years. His ride briefly brings him into Earth's orbit, making Ryugu a potentially dangerous asteroid.
The orbit also made Ryugu an interesting candidate for a sample return mission.
The Hayabusa 2 spacecraft arrived in Ryugu in June 2018 and deployed three mobile trackers to cover the surface of the asteroid in September and October, making another first in space exploration.
Hayabusa 2 will leave Ryugu in November or December and switch on its ion engines to Earth, where it will release a heat shielded landing capsule to land in Australia in December 2020.
"We captured the samples," Tsuda said. "We have to make sure that he comes back to Earth, so we have to continue the operations properly."
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